A four-time All-Pro selection with the Oakland Raiders and graduate of UC Berkeley, Asomugha agreed to a modest one-year deal with San Francisco on Tuesday. According to ESPN's Adam Schefter, the deal is worth just $1.35 million in base salary and contains no guarantees.

Adam Schefter @AdamSchefter

CB Nnamdi Asomugha is signing a 1-yr deal with 49ers worth $1.35 million in base salary, but get this: He didn't want ANY guaranteed money.

Asomugha can likely overlook the monetary aspect for two important reasons.

For one, the Philadelphia Eagles are still paying him $4 million in guaranteed money from the five-year, $60 million deal he signed as one of the biggest free-agent catches of the 2011 offseason.

He likely isn't hurting for cash.

Secondly, and perhaps more importantly, a contract with the 49ers guarantees Asomugha a chance to redeem himself in a defensive system that is much more catered to the philosophies that made him one of the game's best cover cornerbacks while in Oakland.

For the last two seasons, however, Asomugha has regressed into one of the biggest busts in free-agent history. Surely there has been an erosion of his abilities from simply getting older (he'll be 32 in July), but misuse by the Eagles also heavily contributed to his decline.

Asked to play more zone defense than at any other point in his NFL career, Asomugha struggled. Passing off receivers and reading an area of the field were never his strongest points, and when the Eagles increased their demands, the more he struggled.

In 2011—his first year in Philadelphia—Asomugha allowed four touchdowns and gave up a passer rating of 88.6, according to Pro Football Focus (subscription required). Those aren't terrible numbers, but at the time, each represented a new career worst.

Last season, little went right. The Eagles pass defense was one of the worst in football, and Asomugha's struggles adjusting were a big reason why.

Per PFF, Asomugha allowed catches on nearly 67 percent of his targeted passes. Receivers totaled 698 yards and a 15.9-yard average against Asomugha, the seventh-worst mark among NFL cornerbacks. His 305 yards allowed after the catch were the sixth worst. And allowing five passing touchdowns and intercepting just one pass resulted in a passer rating against of 120.6, the fifth-worst in the NFL.

Instead of paying Asomugha almost $12 million in 2013, the Eagles instead took a $4 million guaranteed hit and sent the 31-year-old cornerback packing. The fact that Asomugha received such a minimal one-year deal with zero guaranteed money—despite playing one of the game's premium positions—illustrates just how far his star had fallen in two years in Philadelphia.

However, Asomugha is likely landing in the perfect situation to turn around his career.

Lost in the zone principles of the Eagles defense, Asomugha now lands in one of the game's most man-centered defenses in San Francisco.

According to safety Donte Whitner, who spoke about Asomugha's fit on NFL Network's Total Access Tuesday (via Matt Barrows), the 49ers play close to "70 percent man" defense.

When Nnamdi was in Oakland, they played a lot of press, man-to-man; let him get up there, use his long body, length and size to cover those wide receivers. If you look at our scheme, that's what we do. We play a lot of man - probably 70 percent man. He'll get up in a lot of wide receivers' faces and have an opportunity to use our pass rush, and let those guys work for him. I believe he'll come out and have a great year with us.

Whitner is correct on both accounts.

Fundamentally, defensive coordinator Vic Fangio prefers to play press-man coverage with two safeties high. The idea is for the 49ers front seven to get home to the quarterback while the cornerbacks play in the face of the receivers and the safeties are free to roam, either in the box or at the back end of the secondary.

The look has worked wonders for the 49ers, who have been one of the game's best defenses over the last two seasons. In both 2011 and 2012, San Francisco finished in the top five in both scoring and total defense.

Asomugha should be well-versed in playing the way Fangio wants his cornerbacks to.

According to Neil Hornsby of PFF, Asomugha played 82 percent of his total snaps from 2008 to 2010 at right cornerback, where Oakland asked him to almost exclusively play press, man-to-man coverage.

The result? Quarterbacks simply didn't throw at him.

Over three years of data, Asomugha was targeted the least per snap of any NFL cornerback, and as Hornby's puts it, by "a ridiculous margin."

In 2008, he was targeted just 30 times despite playing 974 snaps. The next season, he was targeted 28 times over 979 snaps. In 2010, just 29 times over 785. Overall, Asomugha faced just 87 targets over three years while still playing nearly 2,800 defensive snaps.

That said, Asomugha will still have to compete against a number of returning cornerbacks in San Francisco for playing time.

Carlos Rogers will make over $7 million in 2013 and should be cemented into one starting spot. Chris Culliver, a 24-year-old former third-round pick, played over 800 snaps last season, both outside and in the slot.

There's also always the chance that San Francisco uses one of its several draft picks on a deep class of cornerbacks.

Most likely, Asomugha will have to beat out incumbent starter Tarell Brown to see significant snaps in 2013. The 28-year-old Brown is coming off his best NFL season, but he stands just 5'10", and the 49ers reportedly want to upgrade.

Greg Cosell, a film guru and executive producer of NFL films, told Matt Maiocco of CSN Bay Area that San Francisco feels "Brown can be upgraded," and that Asomugha is now Brown's "competition."

Throughout the offseason, the 49ers have targeted taller cornerbacks capable of playing at the line of scrimmage.

However, it's worth noting that PFF graded (subscription required) Brown as the 49ers' best cornerback and the NFL's 13th best overall last season.

For Asomugha, the chance to simply win such a competition in a fitting setting will have to be enough.

Asked to play zone, cover from the slot and blitz off the edge more than he had at any point in his NFL career, Asomugha fell in two years from one of the game's most respected cornerbacks to a guy capable of securing nothing more than a one-year deal with no guaranteed money.

The Eagles, after signing off on a $60 million paycheck, asked Asomugha to be more Charles Woodson than the elite player he was in Oakland.

With the 49ers on a one-year, "prove-it" deal, Asomugha can now fall back into the defensive philosophies that made him great with the Raiders. Using his 6'2" frame at the line of scrimmage, Asomugha will be asked to play man-to-man, press coverage in San Francisco.

He'll need to beat out quality competition, but the fit with the 49ers is a solid one for Asomugha. He can't ask for a better situation to wash away the filth of his last two seasons.